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/*
Copyright Claudio Jeker 2024
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE_1_0.txt or copy at
http://www.boost.org/LICENSE_1_0.txt)
*/
/*
* void *make_fcontext(void *sp, size_t size, void (*fn)(boost_context_data));
*/
#define CC64FSZ 176
#define BIAS 2047
#define FP 112
#define SP 128
#define I7 136
.file "make_sparc64_sysv_elf_gas.S"
.text
.align 4
.global make_fcontext
.type make_fcontext, %function
make_fcontext:
save %sp, -CC64FSZ, %sp
# shift address in %i0 (allocated stack) to lower 16 byte boundary
and %i0, -0xf, %i0
# reserve space for two frames on the stack
# the first frame is for the call the second one holds the data
# for jump_fcontext
sub %i0, 2 * CC64FSZ, %i0
# third argument of make_fcontext() is the context-function to call
# store it in the first stack frame, also clear %fp there to indicate
# the end of the stack.
stx %i2, [%i0 + CC64FSZ + I7]
stx %g0, [%i0 + CC64FSZ + FP]
# On OpenBSD stackghost prevents overriding the return address on
# a stack frame. So this code uses an extra trampoline to load
# to call the context-function and then do the _exit(0) dance.
# Extract the full address of the trampoline via pc relative addressing
1:
rd %pc, %l0
add %l0, (trampoline - 1b - 8), %l0
stx %l0, [%i0 + I7]
# Save framepointer to first stack frame but first substract the BIAS
add %i0, CC64FSZ - BIAS, %l0
stx %l0, [%i0 + SP]
# Return context-data which is also includes the BIAS
ret
restore %i0, -BIAS, %o0
trampoline:
ldx [%sp + BIAS + I7], %l0
# no need to setup boost_context_data, already in %o0 and %o1
jmpl %l0, %o7
nop
call _exit
clr %o0
unimp
.size make_fcontext,.-make_fcontext
# Mark that we don't need executable stack.
.section .note.GNU-stack,"",%progbits
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